This invention relates generally to power operated garage doors and specifically to a garage door opening system that complies with residential safety guidelines for use with a door that has multiple panels or sections.
Currently, power operated one-piece garage door opening systems use a dual lift and reverse cable system in conjunction with a jack shaft garage door opener. Such systems, however, do not work with multi-panel or sectional garage doors. The existing mechanisms for moving a one piece door between a vertical closed position and a horizontal open position consist of a pair of vertical guide tracks and a pair of radiused horizontal guide tracks with a pair of guides or rollers on the door engaging the vertical tracks and another pair of guides or rollers engaging the horizontal tracks. The known system includes two separate segments of flexible cable, a lifting segment and a reverse segment, each being attached to the lower guide or roller on the door. The reverse section then travels down around a floor-mounted pulley and then up to a drum that is mounted above the vertical tracks on a jack shaft, commonly known as a torsion bar, that is mounted above the door. The lifting segment travels up from the lower guide and wraps around the drum. The torsion bar is connected to a reversible motorized drive means. As the motorized drive begins to turn the torsion bar, the lift portion of the flexible cable pulls the door upwardly and open, causing the lift portion of the cable to wind around the drum mounted on the torsion bar and the reverse portion of the cable simultaneously to unwind from the drum. Closing the door involves reversing the rotation of the torsion bar causing the lift cable to unwind from the drum while the reverse cable is rewound.
This dual cable system does not work with a multi-panel, sectional door, which is the most common embodiment for residential application. Residential applications must meet strict federal consumer protection agency guidelines that are tested for by Underwriters Laboratory, including inherent reversing requirements if the door encounters an obstruction while closing. In order to meet these requirements, the lift cable and the reverse cable must wind and unwind off the drum at the same rate so that if an obstruction is encountered, the force is instantly transmitted to the motor via the reverse cable and the closing motion of the door is immediately stopped and reversed. Thus, the lift and the reverse cables must be attached at the same point, near the axis of lift at the bottom of the door, in a known embodiment, the cable attachment point is at the same point as the roller near the bottom of the door. Implementation of this known system on a multi-panel, sectioned door will, however, result in the cables interfering with the rollers and binding the movement of the door. The present invention solves this problem.
A principal object and advantage of the present invention is to provide a mechanism for opening and closing a garage door with a plurality of panels or sections with a flexible cabling system that is powered by a reversible motorized jack shaft operating system. Such a system is known in the art for one-piece garage doors, however no equivalent commercial application is known for multi-panel garage doors.
The present invention discloses the novel placement of two pairs of vertical track disposed adjacent to each other together with a pair of radiused horizontal tracks being attached to the outer pair of vertical tracks. Use of an inner and outer pair of vertical tracks disposed adjacent to each other allows the lowermost rollers to be guided on the inner vertical tracks and the remaining rollers to be guided on the outer vertical tracks and, ultimately, the horizontal tracks as the multi-panel, sectional garage door opens. This configuration allows the lift cable a clear pathway to travel from the drum down the center of the inner vertical tracks to the connection with the shaft journal mounted near the bottom of the garage door. The reverse cable also has a free pathway from its connection to the shaft journal at the lower portion of the garage door, down around the pulley located adjacent to the bottom of the garage door and then upwardly toward the back side of the cable drum and, ultimately, to be attached to the drum so that it wraps around the drum as the door closes, or unwraps from the drum as the door opens, without interfering with the rollers. This configuration ensures that the lift and reverse cables move simultaneously, thus maintaining the constant tension in the flexible cabling system necessary to provide the required safety feedback mechanism in case an obstruction is encountered during the closing operation.
The foregoing objects of the invention will become apparent to those skilled in the art when the following detailed description of the invention is read in conjunction with the accompanying drawings and claims. Throughout the drawings, like numerals refer to similar or identical parts.